Linguists have often argued that recursion produces linguistic complexity. However, recursion itself preexisting processes such as lexical insertion, lexical combination, memory stacks, and methods of interpretation. In the brain, recursion is an emergent property of a set of adaptations that involve at least six processing systems. Linguistic complexity arises from the interplay of all six of these systems. The complexity of this neuronal support means that the full complexity of human language could not have arisen fortuitously at some single moment in evolution. However, there is evidence that some pieces of the six systems supporting complexity have developed more recently than others.